Paradigm limitations

[Stolidog]

It seems nonsensical that the earths atmosphere is held to it by gravity which is still an unproven theory when there is no apparent barrier keeping it from being sucked out to space which is a vacuum! Can somebody explain to me how the atmosphere stays around the earth. Also I'd like the answer to somehow include the laws of density and buoyancy as this obviously would be the alternative explaination to gravity should it be proven to not exist after all and that density and bouncy  explains all things up and down. 

[Eise]

Vacuum does not suck.

Gas under pressure pushes away. 

Think about it. Maybe you find the answer yourself now.

[StringJunky]

36 minutes ago, Stolidog said:

It seems nonsensical that the earths atmosphere is held to it by gravity which is still an unproven theory when there is no apparent barrier keeping it from being sucked out to space which is a vacuum! Can somebody explain to me how the atmosphere stays around the earth. Also I'd like the answer to somehow include the laws of density and buoyancy as this obviously would be the alternative explaination to gravity should it be proven to not exist after all and that density and bouncy  explains all things up and down. 

Things with high mass attract things with lower mass. Gases and liquids will layer themselves in decreasing order of density where there's an atmosphere around  a central gravitational source.

[Janus]

Just to elaborate on the answer already given.  Gases are just collections of fast moving particles bouncing off of each other.  The pressure of a gas is a result of the collision of those particles.  If you were to have a container, divided in two with a vacuum on one side and a gas under pressure on the other, The pressure on the dividing wall by the gas is the result of the constant collisions of those fast moving particles with the wall.  If you cut a hole in the wall, the vacuum does not "suck" the gas from its side of the container, but rather, the particles that would have collided with the wall where the hole is have nothing to stop them from passing through to the other side so they will cross over into the vacuum side.  Eventually (how long depends on the size of the hole) there will be just as many particles on one side as the other.  Of course now the same number of particles will be in a larger volume with a larger inner surface area.  While this will not change the force of collision for any given particle with the wall, it does decrease the frequency of collisions with the wall.  This, in turn, decreases the net pressure felt by the wall.

Now the Earth's atmosphere doesn't have a wall to hold it atmosphere, but here is how gravity does the trick.  Take a ball and throw it upwards. It leaves your hand at a certain speed, slows as it climbs, and then eventually comes to a stop and falls back down.  Air molecules are no different, They are bouncing off of each other at high speeds, but in order to escape into space they have to climb just like the ball, and just like the ball they lose speed as they do.  Eventually they lose all their speed and can climb no further.

Now if They had started with enough speed (known as escape velocity), they could have kept going, as gravity gets weaker the higher you go, and it would never be able to rob it of its last bit of velocity.   However, the typical speed for air molecules are much lower than this required speed. (except in the case of light elements like helium and hydrogen, the Earth has a more difficult time holding on to these.)  

The speeds of the air molecules are a function of their temperature. With hotter gasses the molecules have faster speeds. If you were to heat our atmosphere considerably, you could cause it to lose its atmosphere. (Going back to hydrogen and helium, the reason the outer gas giants atmospheres contain them is bot because the planets are large and have strong gravity and they are further from the Sun and thus cooler.  The Sun, on the other hand, which is mostly made of hydrogen, is very hot, but is also very massive, on the order of 1000 times the mass of Jupiter, and it only needs its gravity to hold together. In fact, if it weren't for the heat generated by fusion at its core, its gravity would compress it even smaller than it is.)

Attempting to invoke buoyancy as an explanation for the effects we attribute to gravity is a bit of a non-starter as buoyancy relies on gravity to work. It works on the comparison of different weights and volumes of the object and fluid involved, and you can't have different weights without gravity. It also fails to explain why our space probes follow trajectories influenced by the gravity of the various bodies in the solar system while traveling through a vacuum, which has no buoyant effect. Nor does it explain why object still fall in a vacuum chamber, such as shown here:

 

 

[Strange]

1 hour ago, Stolidog said:

It seems nonsensical that the earths atmosphere is held to it by gravity which is still an unproven theory when there is no apparent barrier keeping it from being sucked out to space which is a vacuum! 

If gravity were an unproved(1) theory(2) then the existence of the atmosphere would be (yet more) evidence for gravity. 

(1) nothing is proved in science. 

(2) gravity is not a theory, it is a fact. But there are theories that explain if (with varying degrees of accuracy)

1 hour ago, Stolidog said:

Can somebody explain to me how the atmosphere stays around the earth.

Gravity. 

Quote

Also I'd like the answer to somehow include the laws of density and buoyancy

Wanting a particular answer is unscientific. Also density and buoyancy are results of gravity, not a cause. 

[Sensei]

On 7/25/2017 at 3:56 PM, Stolidog said:

It seems nonsensical that the earths atmosphere is held to it by gravity which is still an unproven theory when there is no apparent barrier keeping it from being sucked out to space which is a vacuum!

 

Atmosphere can be (and will be in the future of Solar System) wiped out by high enough radiation from the Sun (or other high energy particles source f.e. Gamma Ray Burst). It's just a matter of time.

Particle of atmosphere is here on the Earth just because its velocity relative to Earth is relatively small. High energy particle will give it enough kinetic energy and it'll fly away escaping from the Earth.

Edited July 29, 2017 by Sensei

[swansont]

On 7/25/2017 at 10:38 AM, StringJunky said:

Things with high mass attract things with lower mass. Gases and liquids will layer themselves in decreasing order of density where there's an atmosphere around  a central gravitational source.

According to Newton's third law they attract each other with equal force

[StringJunky]

Just now, swansont said:

According to Newton's third law they attract each other with equal force

Yes, that's true but the lower mass moves the greatest distance doesn't it; it will yield the most in deviating from it's course.

[swansont]

On 7/25/2017 at 9:56 AM, Stolidog said:

It seems nonsensical that the earths atmosphere is held to it by gravity which is still an unproven theory when there is no apparent barrier keeping it from being sucked out to space which is a vacuum! Can somebody explain to me how the atmosphere stays around the earth. Also I'd like the answer to somehow include the laws of density and buoyancy as this obviously would be the alternative explaination to gravity should it be proven to not exist after all and that density and bouncy  explains all things up and down. 

Unproven, as all theories are. But I don't see a lot of people thinking it doesn't exist. Things fall down in a fairly predictable manner, and orbits are similarly predictable. The existence of gravity is about as well-established as you are going to get.

[swansont]

Just now, StringJunky said:

Yes, that's true but the lower mass moves the greatest distance doesn't it; it will yield the most in deviating from it's course.

Because F = ma, meaning a = F/m